Organic EL display devices are self light-emitting display devices having wide viewing-angle characteristics, high visibility, and low power consumption. Thus, in recent years, the organic EL display devices have received attention as next-generation flat panel display devices.
An organic EL display device has a thin film transistor (TFT) substrate, and a first electrode, an organic EL layer, and a second electrode, which are sequentially stacked on the TFT substrate. When TFTs of the TFT substrate are turned on, holes are injected from the first electrode to the organic EL layer, and electrons are injected from the second electrode to the organic EL layer. The electrons in the excited state due to recombination with the holes release deactivation energy when returning to the ground state. This deactivation energy is emitted as light from the organic EL display device.
Silver or silver alloy is preferably used as a material of the first electrode as silver and silver alloy have high light-reflecting and light-transmitting properties. However, the surface of silver and silver alloy is oxidized due to a surface treatment such as etching and an ultraviolet (UV)/ozone treatment, and silver oxide thus produced can degrade electrode characteristics. Thus, a transparent electrode such as indium tin oxide (ITO) is stacked on the surface of a conductive film of silver or silver alloy (e.g., Patent Document 1).